The adolescent drive for autonomy often conflicts with parental needs to maintain control over their teenager's behavior. For families of chronically ill teens, conflict resolution and maintenance of adequate communication are more complex and urgent. For example, adolescents with insulin-dependent diabetes mellitus (IDDM) often display noncompliance with treatment, disease-related maladjustment, poor family communication about treatment and poor glycemic control. Many studies have explored family factors that affect these problems, but little is known about the merits of appropriate interventions. Research on family factors in IDDM indicates that communication and problem solving are ubiquitous, critical determinants of behavioral and metabolic status. Also, the principal investigator's recent cross-sectional study of 18 to 22 year old patients with IDDM suggests that poor adjustment to IDDM in earlier adolescence predicts multiple unfavorable behavioral and health outcomes during the transition to adulthood, illustrating the importance of timely intervention. But, there have been few controlled trials of family interventions. Recent research confirms that Behavioral-Family Systems Therapy (BFT) reduces family conflict and improves family communication and problem solving, but it has not been evaluated in the context of IDDM. Hence, the proposed project is a multicenter, randomized, controlled trial of the relative efficacy of current medical therapy alone or combined with participation in either BFT or an educational support group on teen-parent relations, adolescent adjustment to IDDM, treatment adherence, and glycemic control. Families of 120 adolescents with IDDM will be randomized to one of these conditions for 3 months and followed serially for another 12 months. Repeated assessments at 0, 3, 9 and 15 months after enrollment will permit evaluation of the efficacy of BFT. The study will also assess generalization and maintenance of behavior change and analyze processes mediating therapeutic change. The study will also establish a longitudinal database that could yield information about factors affecting persistent maladjustment to IDDM through early adulthood. To the extent that families of adolescents with other chronic diseases face comparable demands, the project will also provide pertinent information about these diseases.